The promise of stem cell therapy has been widely publicized in the past few years. Bone marrow transplantation has been the first practical use of stem cell replacement therapy; however, the possibility that stem cells can be isolated from other tissues has generated enthusiasm that similar treatments could have potential in other areas of medicine. While the practical application of stem cell transplantation for treating nervous system disorders is a long way off, we have recently found that the chicken eye has a zone of progenitor cells at the ciliary margin highly reminiscent of the long recognized stem cell zone of cold-blooded vertebrates. In addition, we have also found that the margin of the adult monkey retina contains cells that have the potential to generate some retinal cell types. We have just begun to characterize the cells of the retinal margin in birds and primates, and we propose a number of experiments that will enable us to determine how similar these cells are to their counterparts in lower vertebrates. The possibility that stem cells could be isolated from the adult primate eye might lead to novel approaches to treating a wide variety of eye, diseases that lead to blindness, such as macular degeneration and glaucoma.